Solvent-free printing process for organic transistors using a naphthalene diimide bearing long alkyl chains

Abstract

We developed a solvent-free transfer-printing process for organic semiconductor thin films combining a polymer transfer-printing plate and annealing. This process exploited the isotropic liquid phase of a naphthalene tetracarboxylic acid diimide derivative substituted at the N and N′ positions with ditridecyl alkyl chains (C13). The developed process used the material efficiently; for example, it required less than 0.01 mg of C13 powder to cover an area of ca. 1 cm2. The resulting films were thin (thickness of ∼80 nm), uniform, and highly crystalline. The maximum electron mobility of thin-film transistors containing the C13 thin films reached 0.3 cm2/V. This process offers a new route to prepare highly crystalline organic semiconductor thin films without using any harmful solvents.